Cooling fan

ABSTRACT

A cooling fan includes a frame ( 100 ) and an impeller ( 200 ) with blades ( 240 ) disposed in the frame ( 100 ). The frame ( 100 ) has a base ( 140 ) and a sidewall ( 160 ) extending from a periphery of the base ( 140 ) with an air outlet ( 180 ) defined therein. The base ( 140 ) has an air inlet ( 142 ) and a vent hole ( 148 ) defined therein. The vent hole ( 148 ) is near the air outlet ( 180 ) and between tip portions of the blades ( 240 ) and the sidewall ( 160 ). In a preferred embodiment, the base ( 140 ) has a supporting portion ( 144 ) disposed in the air inlet ( 142 ). Two ribs ( 146 ) extend from a periphery of the supporting portion ( 144 ) towards the base ( 140 ). One of the ribs ( 146 ) is arranged adjacent to the air outlet ( 180 ) and has a changeable width which is gradually increased along a direction from the supporting portion ( 144 ) to the base ( 140 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a cooling fan, and more particularly to a cooling fan having low noise.

2. Description of Related Art

The computer CPU speed has been greatly increased in recent years due to a rapid progress in semi-conductor technologies. The chip surface heat flux is thus higher and higher accordingly. It is becoming a critical challenge on how to remove the heat so that the system can run reliably. The compact space with high flow resistance in a notebook computer environment is even more critical in the heat removal. A fan with higher air pressure is frequently chosen under such a consideration.

A fan in related art is shown in FIG. 3. The fan includes a frame 10 and an impeller 20 disposed in the frame 10. The frame 10 includes air inlets 12, 14 matching the impeller 20 and an air outlet. The impeller 20 includes a hub 22, a base plate 24 and a plurality of blades 26 formed thereon. The blades 26 transfer the intake airflow parallel to the axial direction of the impeller 20 to the outward airflow along the radial direction of the hub 22, and the outward airflow is then expelled out of the air outlet. However, an air outflow in a curved tongue portion 16 of the frame 10 will interfere with the intake airflow of the air inlets 12, 14 and the later air outflow due to adverse airflow, creating many problems such as noise.

For the foregoing reasons, there is a need for a cooling fan which has low noise.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment of the present invention, a cooling fan comprises a frame and an impeller having a plurality of blades disposed in the frame. The frame has a base and a sidewall extending from a periphery of the base with an air outlet defined therein. The base has an air inlet and a vent hole defined therein. The vent hole is in vicinity of the air outlet and between tip portions of the blades and the sidewall of the frame. In accordance with another preferred embodiment of the present invention, a cooling fan comprises a frame and an impeller having a plurality of blades disposed in the frame. The frame comprises a base and a sidewall extending from a periphery of the base with an air outlet defined therein. The base has an air inlet defined therein, a supporting portion disposed in the air inlet and two ribs extend from a periphery of the supporting portion towards the base so as to connect the supporting portion with the base. One of the ribs is arranged adjacent to the air outlet, and the one of the ribs arranged adjacent to the air outlet has a changeable width which is gradually increased along a direction from the supporting portion to the curved tongue portion.

Other advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present apparatus can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present apparatus. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an assembled view of a cooling fan in accordance with a preferred embodiment of the present invention;

FIG. 2 is an exploded, isometric view of FIG. 1; and

FIG. 3 is an exploded, isometric view of a fan in the related art.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-2, a cooling fan of a preferred embodiment of the invention comprises a frame 100, and an impeller 200 disposed in the frame 100. The impeller 200 comprises a hub 220 and a plurality of blades 240 mounted on the hub 220.

The frame 100 comprises a cap 120, a base 140, and a sidewall 160 perpendicularly and upwardly extending from a periphery of the base 140. The cap 120 is mounted on the sidewall 160 with a chamber formed between the cap 120, the base 140 and the sidewall 160. The impeller 200 is disposed in the chamber to blow an outward airflow out of the chamber from an air outlet 180, which is defined in a front of the sidewall 160. A curved tongue portion 190 protrudes inwardly from the sidewall 160, and is adjacent to the air outlet 180 to adjust airflow flowing into the frame 100.

The cap 120 and the base 140 respectively define a first air inlet 122 and a second air inlet 142 therein. The air enters into the chamber via the first and second air inlets 122, 142. The first and second air inlets 122, 142 both are round-shaped in profile. The base 140 includes a rounded supporting portion 144 disposed in the second air inlet 142 for supporting the impeller 200. Two ribs 146 extend from a periphery of the supporting portion 144 towards the base 140 so as to connect the supporting portion 144 with the base 140.

One of the ribs 146 is arranged adjacent to the curved tongue portion 190, and has a width wider than that of the other rib 146. In this embodiment, the rib 146 adjacent to the curved tongue portion 190 is oriented to point to the curved tongue portion 190, and has a changeable width, which is gradually increased along a direction from the supporting portion 144 to the curved tongue portion 190. As a result, the amount of intake airflow of the second inlet 142 is decreased at the curved tongue portion 190. Accordingly, the amount of an air outflow in vicinity of the curved tongue portion 190, which usually flows back to the air inlets 122, 142 to interfere with the intake airflow and the later air outflow, is decreased. Therefore, the fan has low noise.

For further effectively decreasing the noise of the fan, two vent holes 148 are defined in the base 140 adjacent to the curved tongue portion 190. As shown in FIG. 2, the two vent holes 148 are defined between tip portions of the blades 240 and the sidewall 160 in vicinity of the curved tongue portion 190. The vent holes 148 serve to dissipate the air outflow in vicinity of the curved tongue portion 190, which usually flows back to the air inlets 122, 142 to interfere with the intake airflow and the later air outflow. Therefore, the noise of the fan is further decreased.

As mentioned above, the rib 146 with a changeable width and the two vent holes 148 in vicinity of the curved tongue portion 190 suppress the adverse airflow in the airflow passage in vicinity of the curved tongue portion 190. As a result, the outward airflow of the air outlet 180 is more balanced and the noise of the fan is reduced.

In this embodiment, the vent holes 148 are positioned between the wider rib 146 and the curved tongue portion 190. In other embodiment, a frame of a fan may employ only a rib with a changeable width in vicinity of the curved tongue portion, or only two vent holes in vicinity of the curved tongue portion. Additionally, the number of the rib 146 with a changeable width and the vent holes 148 may be changeable, such as one, three or more.

It is believed that the present invention and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A cooling fan comprising: a frame having a base and a sidewall extending from a periphery of the base with an air outlet defined therein, the base having an air inlet and a vent hole defined therein; an impeller having a plurality of blades disposed in the frame; wherein the vent hole is in vicinity of the air outlet and between tip portions of the blades and the sidewall of the frame.
 2. The cooling fan as described in claim 1, wherein the sidewall has a curved tongue portion formed thereon and the vent hole is in vicinity of the curved tongue portion.
 3. The cooling fan as described in claim 2, wherein the curved tongue portion protrudes inwardly from the sidewall and in vicinity of the air outlet.
 4. The cooling fan as described in claim 1, wherein the base further comprises a supporting portion disposed in the air inlet for supporting the impeller and two ribs extending from a periphery of the supporting portion towards the base so as to connect the supporting portion with the base; wherein one of the ribs is arranged adjacent to the air outlet.
 5. The cooling fan as described in claim 4, wherein the sidewall has a curved tongue portion formed thereon and the vent hole is in vicinity of the curved tongue portion; the curved tongue portion protrudes inwardly from the sidewall and in vicinity of the air outlet; the one of the ribs arranged adjacent to the air outlet is in vicinity of the curved tongue portion.
 6. The cooling fan as described in claim 5, wherein the one of the ribs arranged adjacent to the air outlet has a changeable width which is gradually increased along a direction from the supporting portion to the curved tongue portion.
 7. The cooling fan as described in claim 5, wherein the vent hole is positioned between the one of the ribs arranged adjacent to the air outlet and the curved tongue portion.
 8. A cooling fan comprising: a frame having a base and a sidewall extending from a periphery of the base with an air outlet defined therein, wherein the base has an air inlet defined therein, a supporting portion disposed in the air inlet and two ribs extend from a periphery of the supporting portion towards the base so as to connect the supporting portion with the base; wherein one of the ribs is arranged adjacent to the air outlet and has a changeable width which is gradually increased along a direction from the supporting portion to the base; and an impeller having a plurality of blades disposed in the frame supported on the supporting portion.
 9. The cooling fan as described in claim 8, wherein the sidewall has a curved tongue portion formed thereon and the one of the ribs arranged adjacent to the air outlet is in vicinity of the curved tongue portion.
 10. The cooling fan as described in claim 9, wherein the curved tongue portion protrudes inwardly from the sidewall and is disposed in vicinity of the air outlet.
 11. The cooling fan as described in claim 10, wherein the base further comprises a vent hole defined therein, the vent hole being disposed in vicinity of the curved tongue portion.
 12. The cooling fan as described in claim 11, wherein the vent hole is positioned between the one of the ribs arranged adjacent to the air outlet and the curved tongue portion. 